The invention relates to a yarn feeder, and more particularly, to a yarn feeder for textile machines.
Yarn feeders are used to deliver textile yarn to a textile machine, such as a knitting machine or other yarn-using machine. The yarn feeder draws the yarn from a bobbin held on a creel and delivers it to the textile machine at a defined tension and/or in a defined quantity, or furnishes the yarn under defined conditions. Textile machines to which a plurality of yarns are to be supplied simultaneously usually have a plurality of yarn feeders. In medium-sized circular knitting machines, for instance, about 100 yarn feeders per knitting machine are provided. To that end, the machine has an annular retainer on which the yarn feeders can be secured. The yarn feeders then protrude in rays outwardly from the retainer and are disposed closely together.
Yarn feeders of this design often require a yarn feeler lever so that proper and correct yarn feeding can be monitored.
From German Patent DE 3516891 C1, for instance, a yarn feeder for textile machines is known that has a yarn guide drum driven to rotate about a vertical axis. The arriving yarn is guided onto the yarn guide drum, wraps around it several times, and then leads away from it. Both upstream and downstream of the yarn guide drum, a pivotably supported yarn feeler lever rests on the yarn and is held by the yarn in a pivoted position. If the yarn breaks, or if the yarn tension drops markedly, the lever drops downwardly, which is interpreted as an indication of an undesired state.
For drawing in yarns or on startup or in a sampling mode or slow-motion operation, it may be necessary to stop operation of the yarn feeler levers.
A similar yarn feeder is known from U.S. Pat. No. 5,860,298. It has a basic body which is provided on one end with a fastening device for securing to a retainer of a textile machine. A vertically disposed shaft is rotatably supported on the basic body and carries a yarn guide drum on its lower end. On its upper end, the shaft is connected to pulleys acting as a drive device. The yarn is guided via the yarn guide drum by yarn guide elements, which define a yarn travel path. The yarn travel path begins at the end of the basic body remote from the fastening device and leads via the yarn guide drum to an end on the outlet side; this end being located near the fastening device. Yarn guide levers for monitoring the yarn are pivotably disposed upstream and downstream of the yarn guide drum and rest on the yarn.
When a yarn is drawn in, care must be taken that it be threaded in correctly beneath the yarn feeler levers.
It is an object of the present invention to provide a yarn feeder whose construction and operation is more simplified and reliable.
A yarn feeder according to the invention has at least one but preferably a plurality of yarn feeler levers. To that end, a feeler barrier is provided for shifting the yarn feeler lever into a passive state as needed. This can be obtained either alternatively or cumulatively by two procedures. One is shifting the yarn feeler lever to a passive position when the feeler barrier is actuated, and another is shutting off the yarn feeler lever, or in other words interrupting a signal path connected to the yarn feeler lever, upon actuation of the feeler barrier. If the yarn feeler lever is raised upon actuation of the feeler barrier, for instance, then the yarn can be threaded in more easily, and in the ensuing startup or sampling mode (including a slow-motion mode), any sagging of the yarn will not cause the applicable signal to be generated. The yarn feeler lever is passive. This makes operation markedly easier.
The feeler barrier is manually actuatable and is formed by a slide or by a rotatable or pivotable element. A handle is used for actuation, which is disposed on an outer end of the basic body that is easily accessible to an operator in the installed state. If the yarn feeders are to be disposed, for example, on a fastening ring of a circular knitting machine, from which they protrude radially outward, then the disposition of the handle on the end of the basic body remote from the fastening device permits manual access without hindrance, and the position of the feeler barrier can be seen from outside. In this way, an operator can easily gain an overview of the status of the yarn feeder. Furthermore, operation in which all the feeler barriers, for instance, of all the yarn feeders (as a rule about 100 of them) have to be actuated, is made considerably easier.
The yarn feeder has a yarn travel path that extends from a yarn inlet to a yarn outlet. The handle of the feeler barrier is preferably disposed in the vicinity of the yarn inlet. Generally, this also is where other devices are disposed, such as a yarn brake, knot catcher or the like that require occasional visual inspection or manual access. The operating stations of the yarn feeder are thus concentrated in one region.
The handle may be disposed on the flank of the yarn feeder and specifically on the end of it remote from the fastening device. To that end, a handle recess or some other indentation may be formed in the basic body, which is preferably is formed as a housing. The handle may be visible and accessible in this recess. In addition, it may be connected to or provided with a signaling device, which makes it easier to detect the position of the feeler barrier. By way of example, the signaling device may be a colored slide or the like.
The feeler barrier preferably has, or is formed by, a barrier element, and the barrier element preferably is displaceably supported. The handle can be rigidly joined to the barrier element. This makes for an especially simple, sturdy construction. The barrier element can then be accommodated virtually completely in an interior of the basic body. Still other elements, such as switches, detent means for resiliently defining the position of the barrier element, and the like, can also be accommodated here.
The yarn feeder may have a plurality of yarn feeler levers, which preferably are influenced successively by the feeler barrier. The feeler barrier then successively pivots the yarn feeler levers into the passive position and thus shuts them off in succession. Thus individual yarn feeler levers, such as the yarn feeler lever on the outlet side, can be switched to be passive, in order upon machine startup to activate the yarn feeler on the inlet side for monitoring for yarn breakage, yet allowing brief excessive feed quantities on the outlet side.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: